public async Task <(bool, Message)> TryDequeueAsync()
{
const string sql = @"
delete
from MessageQueue
output deleted.Type, deleted.Payload, deleted.PublishedOnUTC
where Id = (select top 1 Id
from MessageQueue with (readpast)
order by PublishedOnUTC)";
using (IDatasourceConnection connection = await _datasource.GetConnectionAsync())
using (AsyncDbDataReader <IDataReader> reader = await connection.ExecuteReaderAsync(sql))
{
if (await reader.ReadAsync())
{
var ordinalOf = new
{
Type = reader.DbReader.GetOrdinal("Type"),
Payload = reader.DbReader.GetOrdinal("Payload"),
PublishedOnUTC = reader.DbReader.GetOrdinal("PublishedOnUTC")
};
var message = new Message
{
Payload = await reader.Current.GetStream(ordinalOf.Payload).ReadFullyAndDisposeAsync(),
PublishedOnUTC = reader.Current.GetDateTime(ordinalOf.PublishedOnUTC),
Type = reader.Current.GetString(ordinalOf.Type)
};
return(true, message);
}
return(false, null);
}
}
//
// Higher-order utilities
//
public static async Task <int> ExecuteNonQueryAsync(this IDatasourceConnection connection, string commandText,
object parameters = null, bool joinTransaction = true,
CommandType commandType = CommandType.Text, int commandTimeout = -1,
CancellationToken cancellationToken = default(CancellationToken))
{
IDbTransaction tx = null;
if (joinTransaction)
{
tx = LocalTransaction.Current?.DbTransaction;
if (tx != null && !ReferenceEquals(tx.Connection, connection.DbConnection))
{
tx = null;
}
}
using (IDbCommand cmd = connection.DbConnection.CreateCommand(commandText, commandType, commandTimeout, tx))
{
if (parameters != null)
{
cmd.AddParametersWithValues(parameters);
}
return(await cmd.ExecuteNonQueryAsync(cancellationToken));
}
}
public async Task EnqueueAsync(Message message)
{
const string sql = "insert into MessageQueue(Type, PublishedOnUTC, Payload) values(@Type, @PublishedOnUTC, @Payload)";
using (IDatasourceConnection conn = await _datasource.GetConnectionAsync())
{
await conn.ExecuteNonQueryAsync(sql, new { message.Type, message.PublishedOnUTC, message.Payload });
}
}
public static async Task <AsyncDbDataReader <T> > ExecuteReaderAsync <T>(this IDatasourceConnection connection, string commandText,
object parameters = null, bool joinTransaction = true,
CommandType commandType = CommandType.Text, int commandTimeout = -1,
CommandBehavior behavior = CommandBehavior.Default,
CancellationToken cancellationToken = default(CancellationToken))
where T : new()
{
IDbTransaction tx = null;
if (joinTransaction)
{
tx = LocalTransaction.Current?.DbTransaction;
if (tx != null && !ReferenceEquals(tx.Connection, connection.DbConnection))
{
tx = null;
}
}
IDbCommand cmd = null;
IDataReader reader = null;
try
{
cmd = connection.DbConnection.CreateCommand(commandText, commandType, commandTimeout, tx);
if (parameters != null)
{
cmd.AddParametersWithValues(parameters);
}
reader = await cmd.ExecuteReaderAsync(behavior, cancellationToken);
return(new AsyncDbDataReader <T>(reader, cmd, null, ConvertByColumnNames <T>));
}
catch (Exception)
{
reader?.Dispose();
cmd?.Dispose();
throw;
}
}
public static async Task <AsyncDbDataReader <IDataReader> > ExecuteReaderAsync(this IDatasourceConnection connection, string commandText,
object parameters = null, bool joinTransaction = true,
CommandType commandType = CommandType.Text, int commandTimeout = -1,
CommandBehavior behavior = CommandBehavior.Default,
CancellationToken cancellationToken = default(CancellationToken))
{
IDbTransaction tx = null;
if (joinTransaction)
{
tx = LocalTransaction.Current?.DbTransaction;
if (tx != null && !ReferenceEquals(tx.Connection, connection.DbConnection))
{
tx = null;
}
}
IDbCommand cmd = connection.DbConnection.CreateCommand(commandText, commandType, commandTimeout, tx);
if (parameters != null)
{
cmd.AddParametersWithValues(parameters);
}
IDataReader reader = await cmd.ExecuteReaderAsync(behavior, cancellationToken);
return(new AsyncDbDataReader <IDataReader>(reader, cmd, null, x => x));
}
public DeferredDisposingDatasourceConnection(IDatasourceConnection @delegate)
{
Delegate = @delegate;
}
